Astronomy and Celestial Phenomena

 We always see the same face of the moon, because it takes equal time for revolution around the earth and rotation on its own axis.

Rotation of Earth on its axis causes day and night but the revolution of Earth on a tilted axis causes the variation in the length of daytime and night time.

Light from the Sun takes approximately 8 minutes and 20 seconds to reach Earth, which is about 499 seconds. This is based on the average distance of 150 million kilometers between Earth and Sun, and the speed of light at 300,000 km/s. The precise value varies slightly due to Earth's elliptical orbit.

Earth Revolve around the sun in the elliptical orbit

Earth Hour is about climate change awareness and energy conservation. While 'energy crisis' is not the modern framing, the event emphasizes reducing energy consumption. The answer is technically correct as the event relates to energy issues.

The average Earth-Sun distance (approximately 149.6 million km) defines one astronomical unit (AU). A light year is the distance light travels in one year, while a solar day is Earth's rotation period. The term solar day is sometimes used to describe Earth's orbital position relative to the Sun, though this is less common terminology.

The corona is the Sun's outer atmosphere consisting of extremely hot plasma (temperatures in millions of degrees). It appears as a halo or crown around the Sun and is most visible during total solar eclipses or with specialized telescopes called coronagraphs.

During the Perseid meteor shower, Earth passes through debris from Comet Swift-Tuttle, causing visible streaks of light (meteors) across the night sky. The sky does not become overcast or too bright - meteor showers are best visible in dark, clear skies.

The new moon phase occurs when the moon is between Earth and the Sun, with its illuminated side facing away from Earth. This makes the moon virtually invisible from Earth. During this phase, the moon rises and sets approximately with the Sun, so it's not visible in the night sky. A crescent moon shows a sliver of light, full moon is fully illuminated, and waxing/waning refer to the transition between phases.

It is qualifying the verb 'revolves'. Hence round is used as an adverb here.

A cosmic year (also called galactic year) is the time taken for the Sun to complete one orbit around the center of the Milky Way galaxy, approximately 225-250 million Earth years. A light year is a unit of distance. An astronomical year refers to Earth's orbit around the Sun.

Ptolemy, the Greek astronomer who lived in the 2nd century AD, developed a comprehensive model explaining lunar phases. His work in the Almagest described how the changing positions of the Sun, Earth, and Moon create the different phases we observe from Earth.

The heliocentric model places the Sun at the center of the solar system with planets orbiting around it. This model, championed by Copernicus, replaced the Earth-centered geocentric model and is the foundation of modern astronomy.

Kepler's first law states that planets orbit the Sun in elliptical paths with the Sun at one focus of the ellipse. This means the orbit is not a perfect circle but an oval shape, and the Sun is positioned at one of the two focal points.

The solar system is defined as the Sun and all the celestial bodies that are bound by its gravitational pull, including the eight planets, dwarf planets, asteroids, comets, and other objects that orbit the Sun.